Exhaust Soot Research Articles

EFFECT OF DIESEL ENGINE DECARBONISATION ON SELECTED EXHAUST VALUES

In this article, the authors refer to the measurement of acoustic emission, where they found that this methodology can determine the combustion characteristics in the combustion chamber of the engine and thus it is possible to confirm a better combustion process and overall reduction of engine noise after decarbonization. The formation of diesel exhaust soot is also supported by the authors' paper, in which they describe how such soot is formed and what effect the addition of special mixtures to the combustion process has on the formation of such carbon deposits. The article uses BG technologies for deep engine decarbonization, including intake and exhaust parts. This technology is one of many on the market, but it was only with this technology that the authors managed to achieve the relevant results that this article will introduce to. For the test, we selected vehicles that had a problem to pass at the emission control.

Oxidation-induced variations in the physical and fragmentation characteristics of exhaust soot from DMC-diesel blend: Effect of NO presence in the air atmosphere

This study investigated the changes in physical properties (including morphology, primary particle diameter, fractal dimension, and nanostructure) and fragmentation characteristics of exhaust soot from a modern direct injection diesel engine fueled with diesel (D100) and its blend with 7 vol% of dimethyl carbonate (DMC7) during oxidation processes in air and air-NO atmospheres. Soot particles (D100 soot and DMC7 soot) with specific oxidation degrees (0%, 20%, 50%, and 80%) were produced using a thermogravimetric analyzer, then applied to a high-resolution transmission electron microscopy to generate images. The results exhibited that the morphology for D100 soot and DMC7 soot transformed similarly through oxidation, experiencing an increase in fractal dimension, and a decrease in primary particle diameter, while the introduction of NO to the air accelerated these transformations. Additionally, the nanostructure of both soot particles was gradually ordered through oxidation, as evidenced by longer fringe length, narrower separation distance, and lower tortuosity, while DMC7 soot showed lower order degree compared to D100 soot. Interestingly, the ordering processes of soot nanostructure were decelerated as NO was involved in the oxidation process. Furthermore, the aggregate fragmentation rate for both soot particles declined over the oxidation process, while the possibility for primary particle fragmentation increased overall. Moreover, DMC7 soot exhibited significantly lower aggregate fragmentation rate and higher possibility for primary particle fragmentation than D100 soot at the same oxidation stage. This suggests that DMC7 soot is more susceptible to internal oxidation compared to D100 soot. Furthermore, the presence of NO in the air promoted aggregate fragmentation, while reducing the possibility of primary particle fragmentation.

Electrostatic vehicle exhaust particle sensor for the evaluation of the diesel particulate filter (DPF)

A real-time electrostatic particle sensor has been developed to measure the concentration of soot in diesel exhaust. Based on the Venturi effect, the self-priming sampling probe of the sensor was designed to generate a pressure difference to drive particles into the detection region of the electrostatic trap. A detection module was developed for real-time measurement of the nanoamp current generated by charged soot within the probe. The microcurrent was amplified by the signal processing system of the sensor. To guarantee the precision of particles, it was essential to test the performance. The sensor was able to measure currents from −100 nA to −30 nA with a relative error of −0.01%. In addition, experiments comparing the sensor with a commercial instrument have shown that they correlate well. Furthermore, the standard deviation of the sensor was 0.001049 during a 36 h long-term test, which is lower than a commercial instrument with better stability. The sensor was investigated to demonstrate the detection of diesel particulate filter (DPF) failure. The results showed that the consistency between the sensor and the regulatory measurement equipment was good. The data ratios of the sensors installed at the front and rear of the DPF differed by many fold, which indicated that the sensor was able to determine the status of the exhaust system.

Magnesium borate whiskers/La2-XCeXZr2O7 catalysts preparation on cordierite honeycomb ceramic surfaces for soot catalytic oxidation͏

Magnesium borate whiskers were used to prepare a hierarchical microstructure on cordierite ceramic substrate through the precipitation-molten salt method. The La2-XCeXZr2O7 catalyst was then loaded onto the magnesium borate whiskers to form the hierarchical microstructure. The Ce-doped catalysts exhibited a significant improvement in the catalytic activity of soot combustion compared to the La2Zr2O7 catalyst. The study employed various techniques to characterize the structural morphology and phase composition, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The growth of Magnesium borate whiskers (Mg2B2O5) with diameters of 100–200 nm and lengths of 2–5 μm were grown and tightly bonded to the cordierite ceramic substrate to mimic the structure of human respiratory system cilia. This could improve the filtration efficiency of soot in car exhaust. BET analysis showed that the specific surface area of cordierite increased from 0.684 m2/g to 1.363 m2/g after whisker growth. The study confirmed that the whiskers were firmly attached to the cordierite ceramic substrate, as demonstrated by the binding strength experiments. The addition of Ce metal has been found to significantly enhance soot combustion due to the presence of more active oxygen species and superior mobility of lattice oxygen species with more oxygen vacancies. The catalyst's intrinsic redox property was characterized using X-ray photoelectron spectroscopy (XPS) and H2 temperature-programmed reduction (H2-TPR). The semi-quantitative thermogravimetric analysis (TG-DTG) and the temperature-programmed oxidation (TPO) of catalysts showed that Z-La1.9Ce0·1Zr2O7 exhibited the highest catalytic activity for soot combustion, with an ignition temperature of 268 °C, a peak temperature of 418 °C, and a temperature of 90 % soot conversion of 464 °C. Furthermore, cyclic stability experiments demonstrate that the Z-La1.9Ce0·1Zr2O7 catalyst exhibits excellent structural stability and consistent catalytic performance. This distinctive microstructure holds great potential for applications in the field of DPF.

Heteroatom Doping in Pollutant Diesel Soot-Derived Nanocarbon for Enhanced Zn-Ion Storage Performance.

Herein, we have isolated onion-like nanocarbon (ONC) from the exhaust soot of diesel engines and further doped it with nitrogen (N) and sulfur (S) to fabricate N,S-co-doped ONC (N-S-ONC). To explore its application feasibility, we have assembled an aqueous Zn-ion hybrid supercapacitor (ZIHSC) with a N-S-ONC cathode, which attains high specific capacitance with good rate capability. In-depth analyses suggest that the mechanism of charge storage in the ONC is governed by both capacitive-controlled and diffusion-controlled processes, with the capacitive processes leading at all sweep rates. The ZIHSC demonstrated a good energy density of 50 Wh/kg, a maximum power density of 3.6 kW/kg, and an impressive cycle life with 73% capacitance retention after 50,000 charge-discharge cycles. The study suggests the potential possibly for the long-term application of BC derived nanocarbon in electrochemical energy storage systems (EESSs).

On Nucleation Pathways and Particle Size Distribution Evolutions in Stratospheric Aircraft Exhaust Plumes with H2SO4 Enhancement.

Stratospheric aerosol injection (SAI) is proposed as a means of reducing global warming and climate change impacts. Similar to aerosol enhancements produced by volcanic eruptions, introducing particles into the stratosphere would reflect sunlight and reduce the level of warming. However, uncertainties remain about the roles of nucleation mechanisms, ionized molecules, impurities (unevaporated residuals of injected precursors), and ambient conditions in the generation of SAI particles optimally sized to reflect sunlight. Here, we use a kinetic ion-mediated and homogeneous nucleation model to study the formation of H2SO4 particles in aircraft exhaust plumes with direct injection of H2SO4 vapor. We find that under the conditions that produce particles of desired sizes (diameter ∼200-300 nm), nucleation occurs in the nascent (t < 0.01 s), hot (T = 360-445 K), and dry (RH = 0.01-0.1%) plume and is predominantly unary. Nucleation on chemiions occurs first, followed by neutral new particle formation, which converts most of the injected H2SO4 vapor to particles. Coagulation in the aging and diluting plumes governs the subsequent evolution to a narrow (σg = 1.3) particle size distribution. Scavenging by exhaust soot is negligible, but scavenging by acid impurities or incomplete H2SO4 evaporation in the hot exhaust plume and enhanced background aerosols can matter. This research highlights the need to obtain laboratory and/or real-world experiment data to verify the model prediction.

Surfactants and Microbial Aerosol of Urban Particulate Matter (PM10) in Kuala Lumpur City Centre

Surfactants in the atmosphere potentially influence the global climate and may affect human health. This study aims to determine the compositions of surfactants extracted from urban particulate matter (PM10) and motor vehicle exhaust soot. In addition, microbial aerosol was also determined. A high-volume air sampler (HVAS) has been used to collect PM10 samples in Kuala Lumpur urban area. Meanwhile, the vehicle exhaust soot was collected randomly from the exhaust pipes of various types of diesel and petrol vehicles, using a soft brush during dry days. The concentration of anionic surfactants as Methylene Blue Active Substances (MBAS) was determined by the colorimetric method using a UV-Vis Spectrophotometer. The presence of microorganisms such as bacteria and fungi were investigated by colony count. In addition, the correlation between surfactants and traffic-related air pollutants has also been investigated. Results revealed that the average concentration of MBAS in particulate matter is 107.68 ± 7.91 µgm-3. Diesel vehicles demonstrated higher surfactant concentration in exhaust particulate matter with an average value of 0.227 ± 0.006 µmolg-1 compared to petrol vehicles (0.146 ± 0.003 µmolg-1). Based on this study, various mitigation procedures can be implemented to reduce the impacts of PM and exhaust soot for a better future.

Multi-heteroatom doped vehicle exhaust soot derived nano-onion based economical and efficient electrodes for microbial fuel cell: A waste to wealth strategy

Multi-heteroatom doped vehicle exhaust soot derived nano-onion based economical and efficient electrodes for microbial fuel cell: A waste to wealth strategy

Vehicle exhaust soot used to make a microbial fuel cell

Vehicle exhaust soot used to make a microbial fuel cell

Diesel soot combustion in air-NO environment: Evolution of soot physical properties and fragmentation characteristics

Since the oxidation activity of nitrogen oxides on soot is obviously higher than that of O2, it is one of the most effective means to improve soot combustion in diesel particulate filter (DPF) by fully utilizing the oxidation activity of nitrogen oxides in diesel exhaust. This paper investigated the physical properties (i.e. morphology, primary particle diameter, fractal dimension and nanostructure) and oxidation-induced fragmentation characteristics of diesel exhaust soot particles during oxidation degrees (0 %, 20 %, 50 % and 80 %) in different atmospheres (air, air-1000 ppm NO and air-2000 ppm NO). The results showed that during the oxidation process the variation trends of soot morphology in air and air-NO environments were similar, while the number and size of primary particles in an aggregate decreased and the fractal dimension of the aggregate increased with the presence of NO in air atmosphere. With the progress of oxidation, the nanostructure of soot particles became more ordered, while this variation trend was slowed down when NO was added to the air atmosphere. This is because soot particles oxidized in air-NO atmospheres showed less probability of internal oxidation but more external oxidation than those in air atmosphere. Over the oxidation process, the soot aggregate fragmentation rate presented a decreasing variation trend under each oxidizing atmosphere, with a higher aggregate fragmentation rate and more apparent variations in air-NO atmospheres. Moreover, in the air atmosphere, the probability of primary soot particle fragmentation showed a consistent upward trend, while the addition of NO slowed down this trend and showed an upward trend in stages 1(0 % ∼ 20 %) and 2(20 % ∼ 50 %), but a downward trend in stage 3(50 % ∼ 80 %). This suggests that the addition of NO reduces the probability of oxidants (especially O2) entering the particles, which would lead to a decrease in the probability of primary soot fragmentation caused by internal oxidation.

Oxidation of soot in gasoline exhaust on Mn2O3 catalyst

A Mn2O3 catalyst was investigated for soot oxidation in gasoline exhaust. Catalytic studies performed in model exhaust with Mn2O3/soot mixtures in tight contact showed efficient soot oxidation above 250 °C. This high performance was additionally confirmed on a gasoline engine test bench using a Mn2O3-coated particulate filter. The mechanism of the oxygen transport from the gas phase to soot was investigated by kinetic modeling of O2 adsorption and desorption as well as catalytic studies using 18O2. As a result, it was suggested that O2 dissociatively adsorbs on Mn2O3 followed by surface migration and transfer of oxygen to the soot at physical contact points between the two solids. The surface, sub-surface and bulk oxygen of the catalyst were also found to play a role. Enhanced participation of bulk oxygen appeared with declining O2 content due to partial reduction of Mn2O3 and formation of oxygen vacancies driving the oxygen mobility.

Characterization of soot emissions formed in a compression ignition engine cofired by ammonia and diesel

The impact of ammonia (NH3) co-firing with diesel on the greenhouse gases (GHG) and soot emissions of compression ignition (CI) engines is a current concern in large-scale agriculture, marine transportation and shipping applications for which NH3 is proposed as a near-term decarbonization solution. In this study, the effect of NH3 port injection on the GHG emissions and the characteristics of the soot formed in a NH3-diesel dual fuel CI engine is investigated. Soot is sampled from the engine exhaust operating in dual-fuel mode at 20% and 40% NH3 energy fraction and in diesel-only mode at a fixed engine speed, load, and diesel injection strategy. Detailed analysis of soot is done to investigate: the exhaust soot yield using gravimetric analysis, soot growth and inception through the average primary particles size and number concentration using analysis of Transmission Electron Microscopy (TEM) imaging, the soot nanostructure using Raman spectroscopy, and the chemical composition using X-ray Photoelectron Spectroscopy (XPS). The engine GHG emissions measurements shows that carbon dioxide (CO2) is reduced while N2O emissions increases with NH3 addition. The engine soot emissions yield is significantly reduced with the average primary particles size and number concentration decreasing as the NH3 energy fraction increases. The soot nanostructure is impacted by NH3 addition as it becomes more graphitic with high ratio of sp2 to sp3 carbon bonding. The XPS chemical composition analysis also shows an increase in the nitrogen bonding with carbon in the aromatic rings on the particles surface. The results suggest that the chemical interaction of NH3 with diesel results in soot with more graphitic nanostructure as nitrogen reaction with carbon at active defect sites leads to an increase in the nitrogen content on the soot surface with NH3 addition. This indicates an increased potential of NH3 co-firing with diesel to form nitrogenated PAHs (N-PAH) on the soot surface which would require further studies to identify the risks posed on the environment and human health.

Dimethyl ether fuel injection system development for a compression ignition engine for increasing the thermal efficiency and reducing emissions

In this study, a dedicated fuel injection equipment (FIE) for a 100% dimethyl ether (DME)-fueled three-cylinder engine was developed. DME has a cetane number (>55) higher than baseline diesel (40–50), making it a promising compression ignition (CI) engine fuel. However, some physicochemical properties of DME, namely lubricity, viscosity, density, calorific value, vapour pressure, incompatibility with elastomers, etc., necessitate modifications in the existing FIE to deliver a power output equivalent to baseline diesel fuelled engine. Modifications included customized DME storage tanks, supply lines, return lines, and a pneumatic pre-supply feed pump. In addition, a customized high-pressure pump (HPP) (inline mechanical pump) and a set of modified injectors with larger nozzle hole diameters were used for the DME engine. The engine speed was varied from 1000 to 2000 rpm, and off-road operating conditions were simulated using a non-road steady cycle (NRSC). A detailed evaluation of the FIE for its comparative combustion, performance, and emissions characteristics of DME was conducted vis-à-vis baseline diesel. The DME-fuelled engine showed an increase of ∼4.7% in brake thermal efficiency (BTE) under full load conditions and an increase of ∼8.32% BTE under simulated non-road-testing conditions. In addition, the DME-fuelled engine exhibited no visible smoke and negligible soot in the engine exhaust. DME combustion reduced HC emissions by ∼50% at low and medium engine speeds, and a ∼100% reduction was seen at higher engine speeds compared to baseline diesel engine. The CO emission decreased by ∼90%, and the CO2 emissions were ∼15% lower for DME. Lower exhaust gas temperature (EGT) and lower heat release rate (HRR) during premixed combustion indicated that DME-fuelled engine acted as a low heat rejection (LHR) engine. This study demonstrated a 100% DME-fueled engine with a customized FIE, delivering higher thermal efficiency and lower emissions than conventional diesel engines for on- and off-road applications.

Soot particles undergo in-cylinder oxidation again via EGR recirculated gas: Analysis of exhaust soot particle characteristics

Exhaust gas recirculation (EGR) is one of the effective methods to control NOx emission from diesel engine. The present study focused on the amount of soot particles that are back into the engine cylinder via EGR recirculated gas, to explore its influence mechanism on exhaust soot particle characteristics. A DPF (diesel particulate filter) was integrated in EGR loop, which was employed to remove recirculated soot particles and reduce PM emissions. A comprehensive set of experimental techniques were used to characterize the morphology, nanostructure, surface functional groups and oxidation behaviors of soot particles. Results revealed that when soot particles underwent in-cylinder oxidation again via EGR recirculated gas, exhaust soot particles had smaller primary particle size (dp), longer fringe length (La), smaller separation distance (Ds) and tortuosity (Tf), as well as lower relative amount of aliphatic C–H group and oxidation reactivity. Due to higher graphitization degree of recirculated soot particles, the internal burning was conducted earlier during oxidation processes, which resulted in hollow structure at 50% and 75% burn-off stages.

Visible-light promoted hydrogen production by diesel soot derived onion like carbon nanoparticles

Visible-light-driven photocatalytic water splitting has always been considered a promising approach to hydrogen generation. The onion-like carbon nano particles (OCNPs) isolated from diesel engine exhaust soot have shown their strong capability towards the visible-light promoted hydrogen evolution via water splitting. Under visible light irradiation, the hydrogen evolution rate of OCNPs is ∼1075 μM h−1 g−1 which is quite comparable with the available literature without using any dopant materials or co-catalyst. The evolution of hydrogen using the OCNPs is due to the presence of numerous optically active centers and a high sp3/sp2 interface on the surface of OCNPs, which promoted the process of visible-light assisted photocatalytic water splitting. These waste derived OCNPs can serve as high-performance photocatalytic materials for the visible light-to-hydrogen production and could contribute towards the goal to achieve clean energy.

Correlation between Graphitic Carbon and Elemental Carbon in Diesel Particulate Matter in Workplace Atmospheres.

We investigated the suitability of the graphitic carbon (GC) content of diesel particulate matter (DPM), measured using Raman spectroscopy, as a surrogate measure of elemental carbon (EC) determined by thermal optical analysis. The Raman spectra in the range of 800-1800 cm-1 (including the D mode at ∼1322 cm-1 and the G mode at ∼1595 cm-1) were used for GC identification and quantification. Comparison of the Raman spectra for two certified DPM standards (NIST SRM 1650 and SRM 2975), two types of diesel engine exhaust soot, and three types of DPM-enriched workplace aerosols show that the uncertainty of GC quantification based on the D peak height, G peak height, and the total peak area below D and G peaks was about 6.0, 6.7, and 6.9%, respectively. The low uncertainty for different aerosol types suggested possible use of GC as a surrogate measure of EC in workplace atmospheres. A calibration curve was constructed using two laboratory-aerosolized DPM standards to describe the relationship between GC measured by a portable Raman spectrometer and the EC concentration determined by NIOSH Method 5040. The calibration curve was then applied to determine GC-based estimates of the EC contents of diesel engine exhaust samples from two vehicles and seven air samples collected at a hydraulic fracturing worksite. The GC-EC estimates obtained through Raman measurements agreed well with those found by NIOSH Method 5040 for the same samples at EC filter loadings below 2.86 μg/cm2. The study shows that using an appropriate sample collection method that avoids high filter mass loadings, onsite measurement of GC by a portable or hand-held Raman spectrometer can provide a useful indicator of EC in workplace aerosol.

Effect of lubricating base oil on the oxidation behavior of diesel exhaust soot

In this study, the oxidation behaviors of soot particles from diesel engine when using neat diesel fuel (DF) and lubricating base oil-blended fuel (BBF) were investigated. The changes in the average particle size and nanostructure parameters during soot oxidation process were analyzed. Exhaust particulate matter (PM) samples were collected from a four-stroke, four-cylinder and turbo0charged diesel engine operated under 1200 rpm and 200 Nm. DF and BBF Soot samples with different oxidation weight losses of 20 %, 40 %, and 60 % were obtained by thermogravimetric isothermal oxidation experiments at 600 °C, and the particle size and nanostructure parameters (fringe length, La; fringe tortuosity, Tf) were characterized using high-resolution transmission electron microscopy (HRTEM). Results show that the DF soot particles exhibited an oxidation mode that was initially dominated by surface oxidation and gradually deviated to internal oxidation. Combustion of the base oil increased the soot internal oxidation tendency. HRTEM results showed that as the soot oxidation progressed, the primary particles showed a shell-core, onion-like and hollow structure gradually. The La of the primary particles gradually increased, and the Tf gradually decreased, indicating that the soot layer crystallites were rearranged during the oxidation process, which resulted in a disordered nanostructure that transitioned to a more graphitized nanostructure.

Understanding the reaction kinetics of diesel exhaust soot during oxidation process

The purpose of the present study is to better understand the reaction kinetics of diesel exhaust soot during oxidation process. A thermogravimetric analyzer was used to oxidize real diesel exhaust soot generated from a Euro VI diesel engine under non-isothermal conditions. The Friedman-Reich-Levi method and the Sestak-Berggren model were used to determine the oxidation kinetics. Raman spectroscopy and high-resolution transmission electron microscopy were employed to follow the changes of the soot structure during oxidation. The activation energy gradually increased with increasing conversion level during soot oxidation. The oxidation process of diesel exhaust soot could be described as three-step kinetics, and the calculated conversions fitted the experimental results very well. The kinetic predictions of diesel soot oxidation that were obtained using the proposed kinetic models were more accurate and precise than those with the common first-order model. The structural order increased as oxidation progressed, which was responsible for the increased activation energy. The structural ordering was principally caused by the preferential oxidation of the disordered fraction in the diesel soot, especially for the amorphous carbon, which was oxidized in the initial stage of the oxidation reaction.

An analysis of the in-cylinder soots generated from the main- and post-injection combustion in diesel engines

In modern diesel engines, the exhaust soot primarily comes from the main-injection combustion and post-injection combustion. Therefore, to reduce the diesel soot emissions, it is essential to better understand the soots generated from the main-injection combustion (main-soot) and from the post-injection combustion (post-soot). This work focused on the properties of the main-soot and post-soot during the combustion process, including the primary particle size, nanostructure and soot mass. The in-cylinder soot samples were obtained using a self-developed total cylinder sampling system, and the primary particle size and nanostructure were determined using high-resolution transmission electron microscopy. The isolation of the post-soot was achieved by adding dimethyl ether to the intake gas instead of the real main-injection to create a simulated main-injection combustion environment for post-soot formation. Combustion analysis and numerical simulation results showed that the simulated combustion environment for post-soot formation generated by the DME combustion was very similar to that generated by the real main-injection combustion. During the combustion process, although the main-soot and post-soot exhibit similar variations in the primary particle size, the maximum primary particle size of the post-soot is smaller than that of the main-soot (23.38 nm for the main-soot and 20.51 nm for the post-soot). The main-soot and post-soot show almost the same trends in the nanostructure, as characterized by the fringe length, separation and tortuosity, throughout the combustion process. The introduction of the post-injection accelerates the reduction of the primary particle size of the main-soot and the increase in the structural order of the main-soot. Because a large number of the main-soot particles are oxidized during the post-injection combustion, the post-soot accounts for a considerable proportion in the engine-out soot (i.e., 42%).

Physicochemical analysis of the exhaust soot from a gasoline direct injection (GDI) engine and the carbon black

The purpose of the present study is to understand the physicochemical properties of the GDI soot and determine a GDI soot surrogate for the oxidation investigations. The high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analyzer were used to characterize the soot properties, including the morphology, nanostructure, chemical composition, carbon chemical state and oxidation reactivity. The GDI soot sample was harvested from the gasoline particulate filter equipped on a modern China VI passenger vehicle operated over the Worldwide harmonized Light-duty Test Cycle. The obtained GDI soot comprises large numbers of near-spherical primary particles that cluster together to form aggregates with a mean gyration radius of 123.79 nm, and the mean diameter of primary particles is 27.63 nm. The primary particle exhibits a typical core–shell structure, and the mean values of fringe length, separation distance and tortuosity are 0.836 nm, 0.362 nm and 1.263, respectively. In addition to the carbon element, the oxygen element is another important component of soot particles, accounting for 6.28% of the total number of atoms. The carbon component is mainly composed of sp2 hybridized graphitic carbon and sp3 hybridized aliphatic carbon, and the ratio of sp2/sp3 is 2.02. Moreover, the apparent activation energy of soot sample is determined to be 141.7 kJ/mol. The Special Black 4 (SB4) was assessed as a potential surrogate for the GDI soot. The comparison of physicochemical properties shows that the SB4 and GDI soot have almost the same fractal dimension, gyration radius, primary particle size, fringe length, separation distance, tortuosity, sp2/sp3 ratio and apparent activation energy. The great similarities in physicochemical properties highlight that the SB4 can serve as a good GDI soot surrogate for the soot oxidation investigations.